The present invention relates to an eyeglass frame shape measuring apparatus for measuring a three-dimensional shape of a rim (a lens frame) of an eyeglass frame.
An eyeglass frame shape measuring apparatus, called as a frame tracer, which is so formed that an eyeglass frame is held substantially horizontally by a holding mechanism, and a feeler (a stylus) is moved along a groove of a rim of the frame while it is abutted against the rim groove to detect movement (a position) of the feeler, whereby a three-dimensional shape of the rim is measured, has been heretofore proposed (Reference should be made to Japanese Patent Publications No. JP-A-2000-314617 (U.S. Pat. No. 6,325,700), No. JP-A-2001-174252, No. JP-A-2006-350264 (US2005/0275802), No. JP-A-S62-215814, etc.). Among these related arts, the art now in practical use is the device of a type having a moving base which is rectilinearly moved in a substantially horizontal direction, and a moving shaft which is rectilinearly moved in a vertical direction (a substantially perpendicular direction) with respect to the moving base, in which the feeler is attached to the moving shaft, as disclosed in Japanese Patent Publication No. JP-A-2000-314617 (U.S. Pat. No. 6,325,700).
In order to accurately measure the three-dimensional shape of the rim, it is desirable that the feeler is smoothly moved, while it is abutted against the rim groove with a constant pressure. However, in a rectilinear moving mechanism as provided in the device of Japanese Patent Publication No. JP-A-2000-314617 (U.S. Pat. No. 6,325,700), there is such concern that dust may be likely to enter into the rectilinear moving mechanism, and a trouble may occur in smooth movement of the feeler after a long term use. The rectilinear moving mechanism is partly used in the devices as disclosed in Japanese Patent Publications No. JP-A-2001-174252, and No. JP-A-2006-350264 (US2005/275802).
Moreover, in recent years, demand for eyeglass frames having a large deflection (highly curved frames) has increased. For this reason, it has been desired that even the highly curved frame can be stably measured in such a manner that the feeler may not deviate from the rim groove.